基于纳米金属光栅结构的新型电润湿显示单元的研究

纳米金属光栅的透射光谱对临近材料折射率变化非常敏感,可以通过改变介质折射率实现可调的彩色滤光,将双层纳米金属光栅应用于显示装置上具有工艺制备简单、色度和对比度高等特点.采用纳米金属光栅结构,通过严格耦合波理论模拟和表面等离子体共振原理设计了一种新型的透射式电润湿显示器件.在650 nm周期、空气环境下,通过数值优化在690 nm波长处得到了50％的单色透射,而在水溶液的环境下,由于共振移动到红外,可以实现黑态显示,从而验证了灰度的可调.该研究将为轻薄、节能和高分辨率的新型电浸润显示器件设计提供全新思路.     

用纳米印刷技术制备微机械和微流体金属光栅器件

纳米印刷技术是一种制备大面积亚波长光栅的新技术。基于此光栅的滤光器具有光谱的特性。利用波长耦合分析法对光栅进行理论模拟,此模拟允许反射率取最大和最小值：利用微电子机械系统（MEMS）制备微流体和微机械光栅,这些光栅是制备可调滤光器和其他可选择波长器件的基本元件。这些可调器件通过改变光栅表面的折射率实现波长的选择。如果在光栅表面附着一层水膜。光栅共振波长可改变33％;如果在光栅表面覆盖石英。则共振波长从558nm改变到879nm,波长改变率高达58％。此外,大约有3种因素可改变单一波长的折射率。这些光栅器件在可调滤光器或光调节器方面有着重要的应用价值。     

透射式金属光栅耦合SPR传感器

用磁控溅射技术在双面抛光的蓝宝石衬底上沉积了20 nm Ti和100 nm Au的金属薄膜,通过标准光刻工艺制备出1.6和2.0μm两种周期结构的一维光栅表面等离子体共振(SPR)传感器。用时域有限差分算法(FDTD)模拟仿真并结合实验测试的透射光谱,研究分析了不同周期结构的金属薄膜光栅型SPR传感器的特性。基于金属光栅耦合,利用表面等离子体激元(SPP)的局域特性和光栅的选频特性,实现了SPR传感器的信号增强和滤波功能。研究结果表明,利用金属薄膜光栅表面介质的变化引起的光栅透射光谱中激发表面等离子体共振峰的位置变化,可以获得被测物体的物理、生物和化学等相关特征信息。     

亚波长金属周期结构中表面等离子体相关机理和应用

研究了一种新型的有表面凹槽的亚波长金属光栅结构,通过改变表面凹槽填充物的折射率,可调控该结构的远场透射效率,在光学探测、生物传感等方面具有应用前景;结合金属波导理论,提出一种基于亚波长金属光栅波导结构的新型超分辨光刻方案,入射光波长为436 nm时,最高刻写分辨率可达34 nm.     

基于非对称折变型超长周期光纤光栅的湿度传感器

利用高频CO2激光在普通通信单模光纤上制作了非对称折变型超长周期光纤光栅(ULPFG),由于这种光栅只有较高的外界折射率响应灵敏度,可基于此设计制作高灵敏度湿度传感器.通过在ULPFG的表层涂覆一层具有较强吸水性的新型纳米复合水凝胶,水凝胶通过吸收空气中的水蒸气而使自身的折射率发生变化,从而导致ULPFG透射谱的谐振峰发生漂移,通过检测ULPFG谐振峰的漂移量就实现了对环境湿度参量的传感.实验结果表明,在38%～96%的相对湿度变化范围内,光栅谐振峰的最人漂移量可达约30 nm,比先前一些报道的湿度传感器的灵敏度高出近3倍.     

倒梯形双层金属光栅式偏振分束器

为获得高衍射效率、高消光比、宽带宽及大角度容差的光栅结构，提出了一种在近红外波长区域工作的倒梯形双层金属光栅结构的偏振分束器。该结构引入了一层高折射率介质层，并且将光栅区的光刻胶斜切成倒梯形结构，新的设计增大了光栅的透射效率和消光比。使用严格耦合波分析方法，模拟和优化了偏振分束器的结构参数。结果表明，横磁波及横电波在1 290~1 840 nm波长范围内的透射效率和反射效率分别超过97%和95%。透射和反射的最大消光比分别为33 dB和53 dB。在波长为1 550 nm，入射角为-40~40时，光栅的透射和反射消光比都大于22 dB，达到了高性能偏振分束器的要求。相较于双层金属矩形光栅，所提出的倒梯形双层金属结构表现出更高的透射性与反射性，同时具有更好的设计灵活性。     

金属膜衬底上亚波长介质光栅结构的特性及传感应用

提出亚波长介质光栅-金属膜-石英玻璃衬底结构,根据等效介质理论该结构可等效为由金属-光栅-包覆层构成的单面金属包覆波导,在入射波长和入射角满足一定条件时,发生导模共振(GMR)从而产生光波全吸收现象。根据严格耦合波分析(RCWA)理论进行数值分析发现,等效波导中的TM1 GMR峰尖锐,并且对光栅包覆层的折射率变化非常敏感,角度灵敏度为127.87°/RIU(RIU为折射率单位),波长灵敏度为409.35 nm/RIU,在很大的折射率范围内线性度良好。与全介质GMR传感器和光栅型表面等离子体共振(SPR)传感器相比,该结构通过GMR实现较高灵敏度的同时,其较窄的共振峰使得检测精度更高。     

磁光光纤光栅法布里-珀罗腔的光谱可调性研究

利用传输矩阵法分析了磁光效应和光栅折射率初始相位对磁光光纤布拉格光栅(MFBG)-法布里-珀罗(FP)光谱特性的影响。通过调节外加磁场的大小及方向,能实现MFBG-FP的可调滤波特性,并能控制甚至抵消光栅折射率初始相位差引起的透射峰平移。对于高光栅反射率的MFBG-FP,透射峰位置和波长间隔可由其有效腔长以及等效磁光耦合系数来解析表达。MFBG-FP的磁可调能力会随着FP腔与MFBG的磁光耦合系数比的增加而增强,磁光耦合系数比大于1的MFBG-FP结构的磁可调特性优于相应的MFBG结构。     

在800~1100nm范围内实现基于狄拉克半金属的多波段超材料波导

提出了一种基于Dirac半金属层的具有四个方孔谐振器的超材料波导,其波长范围为800~1100nm。 在共振波长842nm,921nm,1010nm和1061nm处分别获得四个透射峰（70％,61％,72％和63％）。 这些透射峰源自于分布在主腔和腔1、2、3或4中的磁场的干涉增强作用。通过将费米能量从50meV增加到70meV,可以增加四个透射峰并将其转移到更短的波长。 所提出的超材料波导可能在纳米级滤波器,开关或折射率传感器中应用。     

亚波长介质光栅-金属Ag薄膜-周期性光子晶体混合结构的Fano共振传感机理

基于表面等离子体极化激元的传输特性和周期性光子晶体的光学特性,提出了一种在亚波长介质光栅-金属Ag薄膜结构中产生离散态,在周期性光子晶体结构中产生连续态的亚波长介质光栅-金属Ag薄膜-周期性光子晶体混合结构。通过对该结构进行理论分析和传输特性研究,阐述了该结构中Fano共振产生的机理,建立了基于角度调制的Fano共振传感结构模型,并定量分析了结构参数对反射光谱曲线的影响。结果表明:当周期性光子晶体周期层数N=4、光栅周期Λ=258 nm和金属Ag薄膜厚度d_0=27 nm时,该结构的品质因数FOM值高达2.11×10~4,角灵敏度S=40 (°)/RIU。该结构为亚波长介质光栅结构中实现Fano共振提供了有效的理论参考,对光学折射率传感结构的设计具有一定的指导意义。     

Metallic Nanowire Coupled CsPbBr3 Quantum Dots Plasmonic Nanolaser

Plasmonic nanolasers provide a valuable opportunity for expanding sub-wavelength applications. Due to the potential of on-chip integration, semiconductor nanowire (NW)-based plasmonic nanolasers that support the waveguide mode attract a high level of interest. To date, perovskite quantum dots (QDs) based plasmonic lasers, especially nanolasers that support plasmonic-waveguide mode, are still a challenge and remain unexplored. Here, metallic NW coupled CsPbBr₃ QDs plasmonic-waveguide lasers are reported. By embedding Ag NWs in QDs film, an evolution from amplified spontaneous emission with a full width at half maximum (FWHM) of 6.6 nm to localized surface plasmon resonance (LSPR) supported random lasing is observed. When the pump light is focused on a single Ag NW, a QD-NW coupled plasmonic-waveguide laser with a much narrower emission peak (FWHM = 0.4 nm) is realized on a single Ag NW with the uniform polyvinylpyrrolidone layer. The QDs serve as the gain medium while the Ag NW serves as a resonant cavity and propagating plasmonic lasing modes. Furthermore, by pumping two Ag NWs with different directions, a dual-wavelength lasing switch is realized. The demonstration of metallic NW coupled QDs plasmonic nanolaser would provide an alternative approach for ultrasmall light sources as well as fundamental studies of light matter interactions.     

基于Matlab的SPR等离子体显示器仿真的研究

研究了基于表面等离子体波共振效应的一种新型显示器——SPR显示器。表面等离子体波共振效应是指入射光的水平波矢与金属一电介质界面处表面等离子体波波矢相同时产生共振的现象，如果电介质的折射率是一个复数，改变折射率的实部会导致表面等离子体共振波长发生改变（可实现颜色的改变），共振强度不变，折射率越大，共振波长越长；改变折射率的虚部则会导致表面等离子体共振强度发生改变（可实现亮度的改变），共振波长不变，虚部越大衰减越严重。表面等离子体波显示器正是基于这一原理而实现了SPR显示。文章对此显示器的设计做了一定的构想，并采用了Matlab软件对SPR等离子体显示器的显示原理、颜色、亮度及多像素进行了仿真。     

Sensitivity Enhancement of Surface Plasmon Resonance Imaging Using Periodic Metallic Nanowires

A nanowire-mediated surface plasmon resonance (SPR) imaging is numerically investigated for enhanced sensitivity. The results calculated by rigorous coupled-wave analysis present that interplays between localized surface plasmons and surface plasmon polaritons contribute to sensitivity enhancement. Compared to conventional thin film-based SPR imaging measurement, an optimal nanowire structure can provide sensitivity enhancement by 3.44 times as well as highly linear detection property for quantification of surface reactions of interests. This paper demonstrates the potential and limitation for a highly sensitive, label-free, and real-time SPR imaging sensor based on periodic metallic nanowires.     

Direction-Controllable Plasmonic Color Scanning by Using Laser-Induced Bubbles

Because of the subwavelength pixel resolution, long-term stability, and radiation resistance, plasmonic colors show great potential applications in high-resolution color display, high-density information storage, and stable color printing. Herein, laser-induced bubbles are used to realize time- and direction-controllable plasmonic color scanning in a metallic nanohole array, which can give rise to plasmonic colors. When the environment is changed from air to water, the peak wavelength of the metallic nanohole array is redshifted by ≈146 nm, and the color of the metallic nanohole array is changed from purple to yellow. Experimentally, these color changes are demonstrated when the water gradually covers the metallic nanohole array. More importantly, by using laser-induced bubbles, time- and direction-controllable plasmonic color scanning is achieved by controlling the movement speeds and positions of a control laser. Compared to the current state-of-the-art plasmonic color scanning technology, the scanning time by using laser-induced bubbles decreases by four orders of magnitude for the same scanning length. The time- and direction-controllable color scanning provides additional degrees of freedom (scanning time and scanning direction), and it may have potential applications in information display, security, storage, and encoding.     

基于对称型齿波导和纳米盘的类EIT和慢光效应

设计了一种新型的基于金属表面等离子体激元（SPPs）的亚波长金属-绝缘体-金属（MIM）型类电磁诱导透明（EIT）系统,该系统由一个直波导及其两边对称的齿形腔和纳米盘耦合而成。利用耦合模式理论对结构进行分析,并通过时域有限差分方法（FDTD）进行数值模拟。当齿形腔和纳米盘的共振频率相近,可以获得类EIT效应,改变齿形腔的长度和纳米盘的半径可以调节透明窗的位置。该装置可以用作高性能的类EIT滤波器,透过率高达77.5%,半高宽低至35.5 nm,群指数高达65,为高度集成光网络提供了一种新的方法,可应用于波长选择器、超快开关、光存储等设备。     

Direct Growth of Vertically Orientated Nanocavity Arrays for Plasmonic Color Generation

Plasmonic structural colors, arising from resonance interactions between photons and metallic nanostructures, have been developed rapidly for high‐end applications. However, common structural color materials and fabrication methods usually have open plasmonic nanostructures and limited scalability, respectively. Here, a new scheme based on Ag nanowire arrays/SiO₂ composite metamaterial films with subwavelength enclosed nanostructures involved that combine a dielectric gap layer and a metal mirror is presented. The whole stacked structure can be simply prepared only via magnetron sputtering without any other procedures. Specifically, by changing deposition parameters, the geometry size and sub‐10 nm periodic parameters of the structure unit cell array can be finely tuned in a controllable and reproducible way. By experiments and simulations, it is demonstrated how interwire coupled plasmonic transverse modes in vertically orientated nanocavity arrays control multiple nanocavity standing‐wave resonances at visible wavelengths, generating three primary colors‐included bright and saturated colors across a wide gamut. Large‐area and uniform structural colors, whether on rigid or flexible substrates, show angle‐insensitive and air‐stable features. In a wider perspective, this work suggests that the material scheme and fabrication advances represent a robust platform for plasmonic color designing, theory exploring, and large‐scale manufacturing.     

银纳米线表面等离子体波导的传输损耗特性研究

通过远场聚焦光斑激发银纳米线表面等离子体激元(SPP: Surface Plasmon Polariton),并搭建银纳米线路由传输结构改变SPP的传输距离,研究了SPP的传输损耗特性。实验上测量了置于玻璃衬底表面的银纳米线在不同激发波长时SPP的传输损耗系数,发现SPP的传输损耗具有波长依赖性：632.8nm激光激发时,传输损耗系数为0.115 ,780nm激光激发时,传输损耗系数为0.0923 ,即传输损耗系数在长波激发时小,而在短波激发时大。测量结果对基于银纳米线波导的集成微纳光学系统设计有很好的指导作用。     

3-D FDTD Analysis of Gold-Nanoparticle-Based Photonic Crystal on Slab Waveguide

In this paper, metallic photonic crystals (PC) based on 2-D periodic arrays of gold nanoparticles were investigated on indium tin oxide slab waveguides using 3-D finite-difference time domain simulations with nonuniform mesh techniques. The PC effects were studied by changing the lattice constants from 300 to 500 nm. The results obtained indicate that the waveguide-excited plasmon absorption peak of periodic array of gold nanoparticles is tunable from 672 to 707 nm due to the second grating order propagating backward at the grazing angle. The nanoparticle-induced extinction of the waveguide mode was also investigated by varying the slab thickness from 100 to 375 nm. The results show that the extinction peak shifts from 650 to 705 nm. The theoretical results predict that the interactions of the periodic array of gold nanoparticles are strongly affected by the dispersion of the waveguide.      

High Sensitive Gas Sensor Application Based on a Small Defect in Silicon Waveguide

A small defect in silicon nanowire waveguides is applied for gas sensors. Small defects with some special shapes and indexes can produce strong resonances with the incident light and induce large loss. Since the silicon waveguide has air cladding, the position of resonant peaks will be sensitive for the variation of the ambient air composition. The sensor based on the principle has a high sensitivity. As an example, we monitored the change of the position of the resonance peak as a function of alcohol concentrations in air. Results showed that a ~5-mg/L ethanol vapor in the air can result in a ~20-nm wavelength shift of the resonance.     

表面等离子体激元增强薄膜太阳电池研究进展

表面等离子体激元共振是金属纳米结构非常独特的光学特性,对基于表面等离子体激元共振的纳米结构体系的研究已形成了一门新兴的学科,即表面等离子体光子学。可以利用金属纳米颗粒光散射、近场增强以及高度局域的表面等离子体极化激元增强薄膜太阳电池光吸收,提高电池转换效率。当前,表面等离子体光子学应用于太阳电池的设计已成为国际上光伏研究迅猛发展的一个热点。文章主要介绍表面等离子体激元增强薄膜太阳电池光吸收的原理及其在光伏器件中应用的最新研究进展。